Azo-2-amino-4-trifluoromethylthiazoles



United States Patent 2,726,237 AZO-2-AMINO-4-TRIFLUOROMETHYLTHIAZOLES Edmund B. Towne and Hubert M. Hill, Kingsport, Tenn.,

assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application August 16, 1952, Serial No. 304,838 6 Claims. (Cl. 260-158) This invention relates to 2-amino-4-trifluoromethylthiazole and 2-amino-4-trifluoromethyl-S-carbethoxythiazole as new compounds, the process for their preparation and to azo compounds prepared therefrom.

The new thiazole compounds of our invention, as fully shown hereinafter, are valuable intermediates for the preparation of azo dye compounds useful for coloring various textile materials, especially cellulose acetate textile materials. The new thiazole compounds also possess interesting possibilities in the pharmaceutical field because sulfathiazole compounds are readily prepared therefrom. Thus the sulfathiazole compounds having the general formula:

wherein Q represents a hydrogen atom or a carbethoxy group are readily prepared. Because of their formula the new thiazole compounds likewise may have direct utility as medicinals, such as, for example, the control of Blackhead disease in turkeys.

It is an object of our invention to provide new amino trifiuoromethylthiazole compounds. Another object is to provide a satisfactory process for the preparation of the new aminotrifluoromethylthiazole compounds of our invention. A further object is to prepare light and gas fast azo dye compounds from the new aminotrifluoromethylthiazole compounds of our invention. A still further object is to provide dyed cellulose acetate textile materials which have good fastness to light and gas.

2-amino-4-trifluoromethylthiazole is prepared in accordance with the process of our invention by reacting l-chloro- 3,3,3-trifluoropropanone-2 (0 FA) OHaCl) 0 with thiourea. 2-amino-4-trifluoromethyl-S-carbethoxythiazole is prepared in accordance with the process of our invention by reacting the ethyl ester of '2-chloro- 4,4,4-trifiuorobutanone-3 acid (orat Jofiolooooim) 0 with thiourea. The ethyl ester of 2-chloro-4,4,4-trifluorobutanone3 acid can also be named ethyl-2-chloro4,4,4- trifiuoroacetoacetate.

The azo compounds of our invention are represented for the most part by the general formula:

2,2,2-trifluoroethyl group or a 3,3,3-trifiuoropropyl group,

R1 represents a hydroxyalkyl group having 2 to 4, in-

elusive, carbon atoms or an acetoxyethyl group, X represents a hydrogen atom or an alkoxy group having 1 to 2,

inclusive, carbon atoms and Y represents a hydrogen atom, a methyl group, a chlorine atom, a bromine atom, an alkoxy group having 1 to 2, inclusive, carbon atoms, an acetylamino group, a propionylamino group or a butyrylamino group.

The azo compounds of our invention are useful for coloring textile materials made of or containing a cellulose carboxylic acid ester having two to four carbon atoms in the acid groups thereof. They are especially of use for the coloration of cellulose acetate textile materials. When applied to the aforesaid textile materials, they give, for example, red, reddish-violet, violet, orange and orange-red dyeings which, for the most part, have good fastness to both light and gas. The azo compounds of our invention also color wool, silk, nylon, polyethylene terephthalate and modified polyacrylonitrile textile materials similar colors.

By cellulose alkyl carboxylic acid esters having two to four carbon atoms in the acid groups thereof, we mean to include, for example, both hydrolyzed and unhydrolyzed cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate-propionate and cellulose acetate-butyrate.

The azo compounds having the above formula are prepared by diazotizing 2-amino-4-trifluoromethylthiazole or 2- amino-4-trifluoromethyl-S-carbethoxythiazole and coupling the diazonium compound obtained with a compound having the formula:

'Hcc

wherein R, R1, X and Y have the meaning previously assigned to them.

Illustrative of the alkyl groups represented by R are the methyl, the ethyl, the n-propyl, the isopropyl and the n-butyl groups. Similarly the fl-hydroxyethyl, the ,s-hydroxypropyl, the -hydroxypropyl, the ,8,'ydihydroxypropyl, the fi-methyl-p dihydroxypropyl and the fi-hydroxybutyl groups are illustrative of the hydroxyalkyl groups R and R1 represent.

The following examples illustrate the compounds of our invention and their manner of preparation:

EXAMPLE 1 Preparation of 2-amino-4-trifluor0methylthiazole 14 grams of 1-chloro-3,3,3-trifluoropropanone-2 and 7.26 grams of thiourea in 50 cc. of water were heated together on a steam bath for four hours. After cooling, the reaction mixture was made slightly basic with sodium carbonate. A yellow precipitate of 2-amino-4-trifluoromethylthiazole formed and was recovered by filtration and dried. 9.1 grams of product melting at 58 C.60 C. were obtained.

Analysis.Calculated for C4H3F3N2S: C, 28.57; H, 1.79; N, 16.67; S, 19.07. Found: C, 29.22; H, 1.95; N, 16.70; S, 19.28.

EXAMPLE 2 Preparation of 2-amin0-4-trifluor0methyI-S-carbethoxythiazole 9.6 grams of the ethyl ester of 2-ch1oro-4,4,4-trifluorobutanone-3 acid and 3.34 grams of thiourea in 25 cc. of ethyl alcohol were refluxed together for four hours and then the ethyl alcohol present in the reaction mixture was removed by distilling under a vacuum. Following this, cc. of water were added and the reaction mixture was filtered. The solid collected on the filter was suspended in water and sufficient ammonium hydroxide was added to make the reaction mixture slightly basic. The solid present in the reaction mixture was recovered by filtration and dried in an oven. 7.9 grams of 2-amino-4-trifluoromethyl-S-carbethoxythiazole melting at 168 C.- 170 C. were thus obtained.

Analysis.Calculated for C7H7F3N2O2S: C, 35.00; H, 2.94; N, 11.67; S, 13.35. Found: C, 35.06; H, 2.99; N, 11.65; S, 13.50.

EXAMPLE 3 A. Preparation of nitrosyl sulfuric acid 1.52 grams of sodium nitrite were added portionwise to 10 cc. of concentrated sulfuric acid, with stirring, and the temperature of the reaction mixture was allowed to rise to 65 C. The resulting solution was then cooled at 5 C. and 20 cc. of a mixture consistnig of 3 cc. of propionic acid and 17 cc. of acetic acid were added dropwise, with stirring, while allowing the temperature to rise to 15 C. and maintaining it at this temperature during the remainder of the addition.

B. Diazotization The nitrosyl sulfuric acid mixture prepared as described above was cooled to C.- C. and then 4.80 grams of 2-amino-4-trifluorornethyl-5-carbethoxythiazole were added portionwise, while stirring, after which 20 cc. of a propionic-acetic acid mixture prepared as described above were added while keeping the temperature of the reaction mixture at 0 C.5 C. The reaction mixture thus obtained was then stirred at 0 C.5 C. for two hours and excess sodium nitrite present was destroyed by adding one gram of urea. A clear diazonium solution was obtained.

C. Coupling cc. (0.004 mole) of a Z-amino-4-trifiuoromethyl-5- carbethoxythiazole diazonium solution prepared as described in B above were added, with stirring, at 0 C.5 C. to a solution of 0.83 gram of N-ethyl-N-p-methyl-m' dihydroxypropyl-m-toluidine in 10 cc. of a 1:6 mixture of propionic-acetic acid (i. e. 1 part by volume of propionic acid to 6 parts by volume of acetic acid) cooled in an ice bath. After a short time, the reaction mixture was made neutral to Congo paper by adding sodium acetate portionwise and the coupling reaction was allowed to proceed for 20-30 minutes, after which the reaction mixture was poured into ice water. After stirring a short time, the reaction mixture was filtered to recover the dye compound formed on the filter. The dye compound thus obtained was washed well with water and dried. 1.30 grams of the dye compound having the formula:

were obtained. This compound has excellent affinity for cellulose acetate textile materials and colors thern deep, bright reddish-violet shades .having excellent fastness to light and gas. A discharge print was sharp and white.

EXAMPLE 4 10 cc. of a 2-amino-4-trifluoromethyl-5-carbethoxythiazole diazonium solution prepared as described in B of Example 3 were coupled at 0 C.-3 C. with a solution of 0.90 gram of N,N-di-B-hydroxyethyl-Z-methoxy-S-chloroaniline in 10 cc. of a 1:6 mixture of propionic-acetic acid. Coupling and recovery of the dye compound formed were carried out in accordance with the general procedure described in Example 3. 1.25 grams of a compound which dyes cellulose acetate textile materials deep violet shades that have excellent fastness to light and gas were obtained.

EXAMPLE 5 10 cc. of a 2-amino-4-trifluoromethyl-5-carbethoxythiazole diazonium solution prepared as described in Example 3 were coupled with a solution of 0.96 gram of N 5, dihydroxypropyl N-flrmethoxyethyl-m-toluidine. Coupling and recovery of the dye compound formed were carried out in accordance with the general procedure described in Example 3. 1.37 grams of a compound which colors cellulose acetate textile materials bright red-violet shades having excellent fastness to gas and outstanding fastness to light were obtained as a dark powder.

EXAMPLE 6 10 cc. of a 2-amino-4-trifluoromethyl-5-carbetl1oxythiazole diazonium solution prepared as described in Example 3 were coupled with a solution of 0.78 gram of N,N-di-fi-hydroxyethyl-m-toluidine in 10 cc. of a 1:6 mixture of propionic-acetic acid. Coupling and recovery of the dye compound formed were carried out in accordance with the general procedure described in Example 3. The dye compound obtained colors cellulose acetate textile materials red-violet shades having good fastness to light and gas.

EXAMPLE 7 10 cc. of a Z-amino-4-trifiuoromethy1-S-carbethoxythiazole diazonium solution prepared as described in Example 3 were coupled with a solution of 0.84 gram of N- ethyl-N-fl,' -dihydroxypropyl-m-toluidine in 10 cc. of a 1:6 mixture of propionic-acetic acid. Coupling and recovery of the dye compound formed were carried out in accordance with the procedure described in Example 3. The dye compound obtained colors cellulose acetate textile materials red-violet shades having good fastness to light and gas.

EXAMPLE 8 10 cc. of a 2-amino-4-trifluoromethyl-5-carbethoxythiazole diazonium solution prepared as described in Example 3 were coupled with a solution of 0.86 gram of N-fi-hydroxyethyl-N-2,2-difiuoroethyl-m-toluidine in 10 cc. of a 1:6 mixture of propionic-acetic acid. Coupling and recovery of the dye compound formed were carried out in accordance with the procedure described in Example 3. The dye compound obtained colors cellulose acetate textile materials reddish-pink shades having good fastness to light and gas.

By the use of 0.92 gram of N-2,2-difluoro-npropyl- N-B-hydroxypropylaniline in the above example, a dye compound is obtained which colors cellulose acetate textile materials reddish-pink shades which have good fastness to light and gas.

EXAMPLE 9 10 cc. of a Z-amino-4-trifluoromethyl-5-carbethoxythiazole diazonium solution prepared in accordance with the procedure described in Example 3 were coupled with a solution of 0.94 gram of N-n-propyl-N-v-methoxy-flhydroxypropyl-m-toluidine in 10 cc, of a 1:6 mixture of propionic-acetic acid. Coupling and recovery of the dye compound formed were carried out in accordance with the procedure described in Example 3. 1.5 grams of a dye which colors cellulose acetate textile materials bright red-violet shades having good fastness to light and gas and which discharge well were obtained.

EXAMPLE 10 10 cc. of a 2-amino-4-trifluoromethyl-S-carbethoxythiazole diazonium solution prepared as described in Example 3 were coupled with a solution of 0.98 gram of N-fl-hydroxyethyl-N-3,3,3-trifluoropropyl-m-toluidine in 10 cc. of a 1:6 mixture of propionicacetic acid. Coupling and recovery of the dye compound formed were carried out in accordance with the procedure described in Example 3. 1.67 grams of a dye compound which colors cellulose acetate textile materials very bright, deep pinkishred shades that have exceptional light fastness and good fastness to gas were obtained. The dyeings are also characterized in that they discharge to sharp, clear white prints.

EXAMPLE 11 3.36 grams (0.02 mole) of 2-amino-4-tritluoromethy1- thiazole were diazotized in a nitrosyl sulfuric acid, pro pionicacetic acid mixture in accordance with the procedure described in Example 3. 10 cc. of the 2-amino-4- trifluoror'nethylthiazole diazonium solution prepared as described above were coupled at 3.-3 C. with a solution of 0.78 gram of N,N-di-p-hydroxyethyl-m-toluidine in cc. of a 1:6 mixture of propionic-acetic acid. Coupling and recovery of the dye compound formed were carried out in accordance with the generalprocedure described in Example 3. 1.1 grams of a dye which colors cellulose acetate textile materials bright violet-red shades having good fastness to light and gas were obtained.

EXAMPLE 12 10 cc. of a 2-amino-4-trifluoromethylthiazole diazonium solution prepared as described in Example 11 were coupled with a solution of 0.84 gram of N-ethyl-N-flgy-dihydroxypropyl-m-toluidine in 10 cc. of a 1:6 mixture of propionic-acetic acid. Coupling and recovery of the dye compound formed were carried out in accordance with the general procedure described in Example 3. 1.13 grams of a dye which colors cellulose acetate textile materials bright violet-red shades which have good fastness to light and gas were obtained.

EXAMPLE 13 10 cc. of a Z-amino-4-trifluoromethylthiazole diazonium solution prepared as described in Example 11, were coupled with a solution of 0.81 gram of N-fl-hydroxyethyl- N-2,2-difluoroethylaniline in 10 cc. of a 1:6 mixture of propionic-acetic acid. Coupling and recovery of the dye compound formed were carried out in accordance with the procedure described in Example 3. 1.22 grams of a dye which colors cellulose acetate textile materials deep orange-red shades having excellent fastness to light and gas were obtained.

EXAMPLE i4 10 cc. of a 2-amino-4-trifluoromethyl-S-carbethoxythiazole diazonium solution prepared as described in Exsame.-

ample 3 were coupled with a solution of 0.88 gram of N- 5, -dihydroxypropyl-7-methyltetrahydroquinoline in 10 cc. of a 1:6 mixture of propionic-acetic acid. Coupling and recovery of the dye compound formed were carried out in accordance with the procedure described in Example 3. 1.13 grams of a dye compound having the formula:

omonorrcmon N s om I C2HEOOCC/ -N=N C CFs- N H,

were obtained. It colors cellulose acetate textile materials bright violet shades which have good fastness to light and gas.

EXAMPLE 15 10 cc. of a 2-amino-4-trifiuoromethylthiazole diazonium solution prepared as described in Exampe 11 were coupled with a solution of 0.90 gram of N-fl,'y-dihydroxypropyl-7-methylbenzomorpholine in 10 cc. of a 1:6 mixture of propionic-acetic acid. Coupling and recovery of the dye compound formed were carried out in accordance with the procedure described in Example 3. The dye compound obtained has the formula:

emorronomon N S CHa- CH2 110 \C-N=N f g u \0 CFs- -N It colors cellulose acetate textile materials rubine shades which have good fastness to light and gas.

The compounds tabulated hereinafter further illustrate the compounds of our invention. These compounds are prepared by diazotizing the diazo components named Table I [Diazo component: 2-aminoktrifluoromethylthiazole.]

Coupling Component Color 1. N ,N-di-B-hydroxyethy1-m-acetylamiuoauiliue red. 2. N ,N-di-fl-hydroxyethyl-2-methoxy-5-acetylaminoanfline Do. 3. N,N-d -hydroxyethy1-2-methoxy-5-methylaniline Do. 4. N ,N -hydroxyethyl-2,5-dimethoxyaniline Do. 5. N,N 5-hydroxycthyl-2,5-diethoxyaniline Do. 6. N-fl-rncthoxyethyl-N-B-methyl-B, 'y-dihydroxypropyl- Do.

m-toluidine. 7. N-B-ethoxyethyl-N-B-hydroxyethylaniline Do. 8. dN-CHgCH COOCHs-N-B.'y-dihydroxypropyl-m-tolui- Do.

me. 9. N-fl,y-dihyd.roxypropyl-N-Bacetoxyethylaniline Do. 10. N-B-hydroxyethyl-N-E-hydroxybntylaniline Do. 11. N -B-hydroxyethyl-N 19, y-dihydroxypropyl-m-toluidlne. Do. 12. N -ethyl-N-/3-acetoxyethyl-m-t01uidine Do. 13. N-n-propyl-N-BJ:ydroxyethyl-m-toluidine Do. 14. N-n-propyl-N 3,'y-dihydroxypropyl-m-toluid1 Do. 15e1 N-n-propyl-N -fi-methyl-B, 'y-dihydroxypropyl-m-tolui- Do.

me. 16. N-ethyl-N-fl-acetoxyethyl-m-toluidine Do. 17. -B, y-dihydroxypropyl-N-ii,3-difluoro-n-butyl-m-tolorange-red.

n1 me. 18. N 3-hydroxyethyl-N-2,2,2-trlfluoroethyl-m-toluidineorange. 19. N-fi-hyclroxycthylN-2,2-difluoro-n-propylaniline Do. 20. N-B-hydroxycthyl-N-3,3-difiuoropropyl-m-toluidine Do. 21. N-B-hydroxyethyl-N-2,2-difiuoro-n-propylaniline Do. 22. N -B-h ydroxyethyl-N -3,3-difluoro-n-butylaniline. Do. 23. N-B-hydroxyethyl-N -fi-eyanocthy1-m-to\u1d1ne Do. 24. N -n-butyl-N -B,v-dihydroxypropyI-m-tol uidine. red. 25. N-B-hydroxypropyl-N-B-hydroxycthylanlllne Do. 26. N-methyl-N-n-propylam'linc Do. 27. N-CH CHzCO0C2Ha-N-fi-hydroxyethylaniline. orange. 28. N,N-di-fi-hydroxypropylanil1ne red. 29. N ,N-di-B-hydroxyethyl-m-chloroanlline. Do. 30. N,N-di-B-hydroxyethyl-m-bromoaniline. Do. 31. N ,N-di-fl-hydroxyethyl-m-n-propionylarnino n e rubine 32. N,N-di-B-hydroxyethyl-m-n-butyry1aminoaniline Do. 33. N Bn dihydroxypropyl 2,7 dirnethyltetrahydro Do.

qnlnoline 34. N -fl-hyd r0xyethyl-2-methyltetrahydroquinoline D0. 35. N49,'ydlhydroxypropyl-2,5-dimethylbeuzomorpholine. Do.

Table II [Diazo component: 2-amlno-4-trlfluoromethyl-5-carbethoxythiazole] Coupling Component Color 1. N ,N-di-B-hydroxyethyl-m-acetylamiuoanillne red-violet. 2. N,N-di-fl-hydroxyethyl 2 methoxy 5 acetylamino- Do.

an no. 3. N,N-d1-fl-hydroxyethyl-2-methoxy-5-methylaniline Do. 4. N,N-di-B-hydroxyethyI-2,5-dimeth0xyaniline Do. 5. N,N-dl-B-hydroxyethyl-2,5-diethoxyanlline. Do. 6. N -B methoxyethyl N fl methyl 6, dihy Do.

propyl-m-toluidine. 7. N -B-ethoxyethyl-N -fl-hydroxyethylanillne Do. 8. -CHCHC 0 O CHs-N-fl,'Y-dihydroxypropyl-m-toluirubiue.

me. 9. N-fl,'y-dihydroxypropyI-N-B-acetoxyethylanlline Do. 10. N-fl-hydroxyethyl-N-8-hydroxybutylaniline red-violet. 11. N B hydroxyethyl N 5, dihydroxypropyl m Do.

toluidine. 12. N-ethyl-N-B-acetoxyethylm-toluidine Do. 13. N-n-propyl-N-B-hydroxyethyl-m-toluidine Do. 14. N -n-propyl-N-fl,v-dihydroxypropyl-m-tolnidine Do. 15. N n propyl N 5 methyl-B,y-dihydroxypropyl-m- Do.

toluldine. 16. N-ethyl-N-fi-acetoxyethyl-m-toluidine Do. 17. N 6,1 dihydroxypropyl N 3,3 difiuoro n butylpinkish-red.

m-toluidlne. 18. N-fl-hydroxyethyl-N-2,2,2-trifiuoroethyl-m-toluidineorange-red. 19. N -B-hydroxyethy1-N -2,2difluoro-n-propylaniline. Do. 20. N43-hydroxyethyl-N-3,3-difluoropropy1-rn-toluidine Do. 21. N-fi-hydroxyethyl-N-Z2-difluoro-n-propylaniline. D0. 22. N-B-hydroxyethy1-N-3,3-difluoro-n-butylaniline Do. 23. N-B-hydrOXyethyLN-B-cyanQethyl-m-toluidine Do. 24. Nn-butyl-N-B,'y-dihydroxypropyl-m-toluidine red-violet. 25. N-fl-hydroxypropyl-N fl hydroxyethylanlline Do. 26. N -m hyl-N-n-propylaniline Do. 27. N-CHZOHZOOOOZHSN' orange-red. 28. N ,N d1 ,9 rubine. 29. N ,N Do. 30. N,N Do. 31. N,N-dl- -l1ydroxyethyl-m-n-propionylaminoanlline. red-violet. 32. N,N-di-B-hydroxyethyl-m-n-butyrylaminoaniline.. Do. 33. N Bpfidlhydroxypropyl 2,7 dlmethyltetrahydroviolet.

' on 0 me. 34. N -B-hydroxyethyl-2-methyltetrahydroquinollne Do. 35. IN 1-1 5, dlhydroxypropyl 2,5 dimethylbenzomor Do.

p o no.

amass? The azo dye compounds of our invention can be applied to the textile materials named hereinbefore in the form of an aqueous dispersion and are ordinarily so applied. To illustrate, the dye compound is finely ground with a dispersing agent such as sodium lignum sulfonate, Turkey red oil, soap, or an oleyl glyceryl sulfate and the resulting mixture is dispersed in water. The dye bath thus prepared is heated to a temperature approximating 45 C.55 C. and the textile material to be dyed is immersed in the dyebath, following which the temperature is gradually raised to 80 C.-90 C. and maintained at this temperature until dyeing is complete, usually onehalf to two hours. From time to time throughout the dyeing operation, the material is worked to promote even dyeing. Upon completion of the dyeing operation, the textile material is removed from the dyebath, washed with an aqueous soap solution, rinsed well with water and dried.

Widely varying amounts of dye can be used in the dyeing operation. The amount of dye used can be, for example, /3 to 3% (by Weight) of that of the textile material although lesser or greater amounts of dye can be employed.

We claim:

1. The azo compounds having the general formula:

wherein R represents a member selected from the group consisting of an alkyl group having 1 to 4, inclusive, carbon atoms, a hydroxyalkyl group having 2 to 4, inclusive, carbon atoms, an alkoxyalkyl group having 3 to 4, inclusive, carbon atoms, a fi-cyanoethyl group, a CH2CH2COOCH3 group, a CH2CH2COOC2H5 group, a 2,2-difiuoroethyl group, a 2,2-difluoro-npropyl group, a 3,3-difluoropropyl group, a 3,3-difiuoro-n-butyl group, a 2,2,2-trifiuoroethyl group and a 3,3,3-trifluoropropyl group, R1 represents a member selected from the group consisting of a hydroxyalkyl group having 2 to 4, inclusive, carbon atoms and an acetoxyethyl group, X represents a member selected from the group consisting of a hydrogen atom and an alkoxy group having 1 to 2,

8 inclusive, carbon atoms and Y represents a member selected from the group consisting of a hydrogen atom, a methyl group, .a .chlorine atom, a bromine atom, an alkoxy group having 1 to 12, inclusive, carbon .atoms, an .acetylarnino group, a propionylamino group and a .butyrylamino group.

2. The .azo compound having the formula:

S\ CHzCHzOH c 11150 0 045 :--N=N C N CF3U-N CH2CH2OH 3. The azo compound having the formula:

/S\ /C2H5 0 13,0 001: fi-N=N-N\ oFto--N 5 CHICHZOH 4. The azo compound having the formula:

OCH: /s\ 0111c molt C 2H5O 0 0-0 G -N=N N\ om- -N CHzCHzOH 5. The azo compound having the formula:

S\ /OH:CHF2 olmooo -o J-N=N- N\ CFs-E-I I (I: CHrCHzQH 6. The azo compound having the formula: S /C:Hs C2H5OOCC/ C-N=N N\ /OH CF -ll- IQl I CHzC-CHzOH OH:

References Cited in the file of this patent UNITED STATES PATENTS 2,015,161 Schweitzer et al. Sept. 24, 1935 2,401,522 Stoll et al. June 4, 1946 2,409,828 Bock et a1. Oct. 22, 1946 2,464,785 Thompson Mar. 22, 1949 2,659,719 Dickey et a1. Nov. 17, 1953 

1. THE AZO COMPOUNDS HAVING THE GENERAL FORMULA: 